<main>
</main>

function Hello(props) {
  return <p>
    Hello: {props.name}
  </p>
}

Hello.propTypes = { name: React.PropTypes.string };
Hello.defaultProps = { name: "Guest" };

class App extends React.Component {
  render() {
    return (<div>
        <Hello name="ynon" />
        <Hello />
        <Hello />
      </div>);
  }
}

ReactDOM.render(<App />, document.querySelector('main'));